THURSDAY, Nov. 3 (HealthDay News) -- Home-based tests using self-collected vaginal samples could serve as an alternative to the traditional Pap smear tests designed to detect the virus that causes cervical cancer, new study findings show.

While laboratories have confirmed the accuracy of vaginal tests for human papillomavirus (HPV), it's been unclear if they would be as effective as medical office-based Pap smears when women used them at home.

Poor women around the world are especially unlikely to get Pap smears, which require a visit to a medical office, according to the authors of the new study, published online Nov. 2 in The Lancet.

In the study, researchers randomly assigned poor Mexican women aged 25 to 65 to get either a traditional Pap smear or take the vaginal HPV test at home. More than 20,000 women took part in the study.

The HPV test detected four times as many cases of cancer as the Pap smear -- a rate of 30 per 10,000 women versus seven per 10,000, the investigators found. However, the HPV test had a much higher rate of false positives -- tests that inaccurately detected cancer.

Despite the higher false-positive rate, the study authors noted, the home-based tests may be preferable to Pap smears in poor regions because of the challenges of getting Pap smears in these areas.

Commenting on the study, Dr. Alan G. Waxman, professor of obstetrics and gynecology at the University of New Mexico, pointed out that in the United States, about 50 percent of the 12,000 women who are diagnosed with cervical cancer each year have never had a Pap smear.

Many of the women who develop the disease are minorities, he said, "and a proportion are also immigrant women who may come from a country where regular screening is not part of the culture."

Waxman said home-based tests are "the way to go" in poor countries. As for costs, he said the tests wouldn't require office visits.

And while Waxman acknowledged that the home-based tests produce many false-positive results, he added that they are also more sensitive to signs of cancer than Pap smears.

So why not replace Pap smears with HPV tests in the United States? "In the United States, we don't do just one test. Women have multiple Pap tests," Waxman said. Cervical cancer "is a slow-growing process, so you make up for that difference by doing multiple tests over time."

The Lancet study was led by Eduardo Lazcano-Ponce of the Centre of Investigation in Population Health at the National Institute of Public Health in Morelos, Mexico, and Attila Lorincz of the Centre for Cancer Prevention at Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London.